Incidence of Subglottic Stenosis
The incidence of acquired subglottic stenosis ranges from 1.7% to 8% in previously intubated neonates studied retrospectively, and 9.8% to 12.8% in infants studied prospectively. 1
Epidemiology and Risk Factors
Subglottic stenosis can be classified as either acquired or idiopathic. The incidence varies significantly based on patient population and risk factors:
Acquired Subglottic Stenosis
- Neonatal population:
- 1.7-8% in retrospective studies
- 9.8-12.8% in prospective studies 1
- Cardiac surgery patients: Only 0.7% in infants and children following cardiac surgery with cardiopulmonary bypass 2
Primary Risk Factors
- Intubation for 7 days or more
- Three or more intubations 1
- Use of inappropriately large endotracheal tubes (tube size-to-gestational age ratio >0.1) 1
- Young age 2
- Prolonged cardiopulmonary bypass 2
- Prolonged mechanical ventilation 2
Idiopathic Subglottic Stenosis
- Extremely rare condition
- Strong female predominance (98% of cases) 3
- Primarily affects Caucasian women (95%) 3
- Mean age of presentation is 50 years 3
Clinical Presentation
Subglottic stenosis typically manifests with:
- Postextubation stridor (significant marker for moderate to severe stenosis)
- Hoarseness
- Apnea and bradycardia
- Failure to tolerate extubation
- Cyanosis or pallor 1
In preterm infants, apnea may replace stridor due to easy fatigability and paradoxical response to hypoxemia 1.
Prevention Strategies
Several approaches have been proven effective in reducing the incidence of subglottic stenosis:
Reducing duration of intubation:
- Using nasal continuous positive airway pressure (CPAP) instead of endotracheal intubation when possible
- Using CPAP as an adjunct to shorten intubation duration 1
Appropriate tube sizing:
- Maintaining tube size-to-gestational age ratio ≤0.1
- Careful selection of appropriate-sized endotracheal tubes 1
Proper suctioning techniques:
- Avoiding "deep" suctioning
- Using catheters with multiple side holes on several planes
- Restricting passage of suction catheters to the distal tip of the artificial airway
- Using appropriate negative pressure (not exceeding 50-80 cm H₂O) 1
Cuff pressure management:
- Maintaining adequate cuff pressure (20 mm Hg) to prevent aspiration
- Avoiding excessive pressure (>30 cm H₂O) that can cause tracheal ischemia 1
Treatment Approaches and Outcomes
Treatment approaches vary between endoscopic and open surgical techniques:
- Endoscopic management: Used in 80.2% of idiopathic subglottic stenosis cases
- Open reconstruction: Used in 19.8% of cases 3
Endoscopic surgery has a significantly higher rate of disease recurrence compared to open approaches 3. However, tracheostomy is avoided in 97% of patients regardless of surgical approach 3.
For patients with granulomatosis with polyangiitis (GPA)-associated subglottic stenosis, medical therapy with leflunomide has shown promise in extending the interval between surgical dilations 4.
Clinical Pitfalls and Considerations
Misdiagnosis: Subglottic stenosis can be confused with other conditions causing similar symptoms (vocal cord injuries, glottic/subglottic webs or cysts, laryngomalacia, or extrathoracic tracheomalacia) 1
Glottic involvement: In GPA-associated stenosis, glottic involvement may not be present initially but can develop later, leading to increased dysphonia and requiring more frequent surgical interventions 4
Idiopathic vs. acquired: Distinguishing between idiopathic and acquired forms is crucial as treatment approaches and outcomes differ. Idiopathic forms tend to recur despite treatment 5
Delayed diagnosis: Idiopathic subglottic stenosis diagnosis is often delayed and confused with other common respiratory diseases 6
By understanding the incidence, risk factors, and prevention strategies for subglottic stenosis, clinicians can work to minimize this potentially life-threatening complication and optimize patient outcomes.